I haven't kept one myself but in this months PFK June there is a whole double page spread on getting your puffer to feed that I can precis for you.
1. Feed some shell foods such as snails, crustaceans and other shellfish.
2. Hunting puffers benefit from more hard foods to wear teeth down.
3. Lurking puffers do not need as much hard food.
4. If you are struggling to get them to feed you have have to start them on live blood worms, black worms, shrimp or snails.
5. Movement is the key to getting them to accept dead foods.
6. Small puffers should accept frozen bloodworms. Defrost in a bowl with boling water. Then use the current from the filter or an airstone to simulate movement.
7. For bigger puffers meatier foods such as mussels, prawns and krill can be be thawed and skewered. Then bobbed and twisted in front of them. Or tied to thread and dangled in filter current.
8. To wean on to live bloodworm it may help to mix live and dead for a while, especially for lurker type puffers.
9. Many puffers are moody when first moved to a new tank and may not eat for the first week or month. This is not unusual. Patience is the key.
10. Smaller active puffers + juveniles need feeding daily with maybe one day off.
11. As they get bigger change to every other day, then to every 3 days. Fully grown twice a week is enough.
Common frozen foods:
mussels, cockles, krill, shell on prawns, crab, crab legs, blood worms, black worms.
Common live foods:
Snails, crabs, shrimp, earthworms, bloodworms, black worms.
Freeze Dried:
Krill, plankton.
Article by Ian Jefferies June 2007